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  #271  
Old 06-15-2009, 12:42 PM
richms richms is offline
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Why would you change from UHF to VHF? Surely thats a massive step backwards for building penetration and multipathing?
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  #272  
Old 06-15-2009, 02:55 PM
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Robert Grant Robert Grant is offline
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In most cases, a step backward for building penetration, but a step forward when it comes to multipath (also a step backwards for household electrical noise).

VHF also has an advantage through trees and hills, but the real appeal of going back to VHF highband is saving on electrical power. A TV transmitter is generally expected to operate 24/7 and the electric bill for a 1000kW UHF DTV station can be huge. VHF allows more "paper coverage" (coverage according to rules but not necessarily in viewability, and assuring cable/satellite carriage) for a lot less money than UHF.
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  #273  
Old 06-15-2009, 06:54 PM
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WA3WLJ WA3WLJ is offline
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WBAL Baltimore went from 500KW UHF to 5KW VHF

Looks like that is what WBAL wanted was guaranteed CABLE coverage and not too worried about the few over the air households that are still left.
They went back to their original Channel 11 VHF channel , so rabbit-ears are useless just 8 miles from the transmitter.
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  #274  
Old 06-15-2009, 08:49 PM
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wa2ise wa2ise is offline
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Ghosts on VHF won't vary as much than on UHF, especially doe to broadcast towers bouncing around from wind. That tower shake can make the broadcast antennas move a substantial fraction of the carrier wavelength on UHF vs VHF. That means that ghosts at receivers are varying too quick for most DTV receivers to process out the ghost conditions.

Of course the main motivation was mentioned in a post above, to get paper coverage and cable must carry at low electric bill costs.
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